The invention generally relates to perception systems, and relates in particular to scanning systems for use in connection with robotic and other sortation systems that are intended to be used in dynamic environments requiring the robotic or other sortation system to accommodate processing a variety of types of objects.
For example many order fulfillment operations achieve high efficiency by employing a process called wave picking. In wave picking, orders are picked from warehouse shelves and placed at locations (e.g., into bins) containing multiple orders that are sorted downstream. At the sorting stage individual articles are identified, and multi-article orders are consolidated, for example into a single bin or shelf location, so that they may be packed and then shipped to customers. The process of sorting these articles has traditionally been done by hand. A human sorter picks an article from an incoming bin, finds a barcode on the object, scans the barcode with a handheld barcode scanner, determines from the scanned barcode the appropriate bin or shelf location for the article, and then places the article in the so-determined bin or shelf location where all articles for that order have been defined to belong. Automated systems for order fulfillment have also been proposed. See for example, U.S. Patent Application Publication No. 2014/0244026, which discloses the use of a robotic arm together with an arcuate structure that is movable to within reach of the robotic arm.
Other ways of identifying items by code scanning either require manual processing, or require that the code location be controlled or constrained so that a fixed or robot-held code scanner (e.g., barcode scanner) can reliably detect it. Manually operated barcode scanners are generally either fixed or handheld systems. With fixed systems, such as those used at point-of-sale systems, the operator holds the article and places it in front of the scanner so that the barcode faces the scanning device's sensors, and the scanner, which scans continuously and decodes any barcodes that it can detect. If the article is not immediately detected, the person holding the article typically needs to vary the position or rotation of the object in front of the fixed scanner, so as to make the barcode more visible to the scanner. For handheld systems, the person operating the scanner looks for the barcode on the article, and then holds the scanner so that the article's barcode is visible to the scanner, and then presses a button on the handheld scanner to initiate a scan of the barcode.
Automatic barcode scanners are similarly either fixed or hand-held systems, and the same principles apply. In the case of barcode scanners typically used in industrial applications, the possible positions of barcodes must be tightly controlled so that they are visible to the one or more scanners. For example, one or more barcode scanners may be placed in fixed locations relative to a conveyor so that they can scan items, typically boxes, as they pass by scanners. See, for example, U.S. Pat. No. 5,495,097. In these installations the range of placement of the barcodes is comparatively limited as the barcodes are on labels affixed to one of four sides or top or bottom (e.g., if upside down) of a box, which can be presented using simple mechanical means, at orientations optimal for scanning.
In all of these cases, the systems employ sensors, cameras or laser reflectivity sensors, as well as software to detect barcodes and decode them. These methods have inherent limitations that include the range of distances of orientations relative to the detection system, over which they are able to reliably scan barcodes. Firstly, the barcode must be facing the scanner; secondly the range to the barcode must be such that individual elements can be reliably distinguished; and, thirdly, the tilt and skew of the barcode must be such that individual elements can be reliably distinguished. The types of sensors employed, and the robustness of the software detection and decoding schemes determine these performance parameters.
There remains a need, therefore, for an object identification system for robotic and other sortation systems that is able to accommodate the automated identification and processing of a variety of objects in a variety of orientations.